Patent GB-462159-A (GB)
Title: Improvements in or relating to automatic switching systems for interconnection of teletypewriters
IPC: H04L12/18
Filed: 1936-09-18
Abstract: 462,159. Interconnection of telegraph stations. STANDARD TELEPHONES & CABLES, Ltd. Sept. 18, 1936, No. 25447. Convention date, Oct. 5, 1935. [Class 40 (iii)] One station is adapted to be connected to one or any combination of a group of stations over normally disconnected lines by switching devices controlled by the transmitter at the said station or, if this station is an intermediate one in the system, by a retransmitter at this station or the transmitter at an originating station. In the system shown in Fig. 1 for connecting a tape transmitter at station A to stations 60 .. 63, switch 47 is closed when sending is to commence to operate magnet 29 which releases the distributer 40. Messages are sent by the five unit code but line selection is effected when an additional unit (upper line on the tape) is used whereby relay 20 is operated to connect magnets 23 ... 27 to the transmitter. Relay 20 may, as shown, disconnect the distributer from the transmitter, but if it is desired to print locally the designation of selected lines, the distributer may remain connected to operate the local printer magnet 45. When the distributer arm reaches segment 77, the closure of contacts 28 operates selected magnets 23 ... 27 according to perforations 85 and also magnet 22, these magnets operating combination selecting mechanism similar to a printer, but in this case selecting a bar 54 .. 57 for operating one of contacts 50 .. 53 whereby relay 35 is energized in series with the corresponding connecting relay 30 .. 33 of a line leading to a distant teleprinter 60..63. After the distributer has made one revolution, the tape is stepped on and, in the case shown, the transmitter is operated by a second station code 86 which effects selection of a further line in a similar manner. Slow releasing relay 20 holds during station selection and operates 21 to disconnect the distributer from the outgoing lines, and 35 locks up until termination of the message to hold the connecting relays 30 .. 33. The station codes are followed by sixth unit perforations 87 to hold 20 long enough to permit the distant teleprinter motors to pick up speed. The perforations 87 are followed by an ineffective five-unit code 88 to give 20 time to release whereupon 21 falls back, the distributer is connected to the outgoing lines and transmission takes place in the usual manner. This is followed by a stop signal (perforations 93) to stop the distant teleprinters and also to open contact 46 of the local teleprinter whereby relay 35 and the connecting relays are released. The stop signal may be followed by sixth unit perforations 94 to give time for restoration to normal before the commencement of further station selection and transmission. Modifications. In the system shown in Fig. 2, the station selecting arrangements at station A2 are controlled from a distant point B2 which may be a subscriber's sub-station or a central station, the line selector at A2 being similar to that of Fig. 1 except that it is operated by a single magnet 80. When B2 desires station selection, a significant code is sent to operate line magnet 145 of a printer mechanism at A2 which, in response, operates bar 82 to energize 66 followed by 120 and 121 corresponding to 21 of Fig. 1. Magnet 80 of the line selector is thus connected to armature 81 which repeats subsequent station codes to magnet 80 to effect line selection. A preparatory code signal is then sent to operate bar 84 which releases 66, 120, 121 to connect the selected line or lines to the contact of 81 and, after the message has been transmitted, the motor stop signal operates bar 158 to release relay 135 and the connecting relays 130.. 133. The systems of Figs. 1 and 2 may be combined in an arrangement, Fig. 3 (not shown) comprising a perforator at station A2, Fig. 2. In order to provide the sixth code unit used in Fig. 1, for station selection, such selection is preceded by a special signal, from B2, Fig. 2, to operate a magnet in the perforator whereby a sixth perforation is added to the subsequent codes, the magnet being released in response to a further specified signal after station selection has been completed.